Tuesday, 20 October 2009

Amphibian extinctions may not be uniquely high, say scientists

The global extinction crisis facing amphibian populations around the world may be as severe for reptiles like snakes, lizards, turtles and crocodiles.

The findings have been put forward in a scientific review in the journal Diversity.

The scientific review also cites evidence that recent scientific research into amphibian declines far outweighs research into reptile declines, even though both groups of species may be facing a similar extinction threat.

The authors of the paper, based at the University of Sussex and the UK wildlife charity Amphibian and Reptile Conservation, argue that future research should be more equally balanced, so that the investment in research mirrors the extinction risk of each group.

Reptiles in decline

The fragile state of the world’s amphibians was widely recognised in 2004, after release of the IUCN Global Amphibian Assessment. This report found that amphibians were facing a greater number of extinctions and declines than any other taxonomic group for which data were available at the time, with one third of all amphibian species worldwide threatened with extinction.

A Global Reptile Assessment is as yet incomplete but already research is indicating that a similar extinction risk may be facing reptiles too.

In May 2008, studies commissioned by the European Commission and carried out by IUCN, found that Europe’s reptiles and amphibians were in similar degrees of trouble. 22.9% of Europe’s native amphibian species were categorised as threatened with extinction, and 19.4% of reptiles. The study also reported that 4.3% of reptile species in Europe were listed as Critically Endangered, the most serious of the Red List categories. This is double the number of amphibians in the same category.

“It is increasingly clear that amphibians are not alone in facing a major biodiversity crisis,” said lead author Professor Trevor Beebee of the University of Sussex. “Other groups of ‘cold blooded’ vertebrates, notably reptiles and freshwater fishes, are in the same boat.”

The research bias toward amphibian decline studies

In the new study, the authors undertook searches of scientific publications between 2005-2009 under the theme of ‘biodiversity and conservation’, comparing the numbers that contained amphibian-related search terms (such as “frogs or toads") with those containing reptile-related search terms (such as “lizards or snakes”).

The results showed that published scientific papers covering amphibian declines outnumbered papers covering reptile declines by four to one (153 papers to 42 respectively), even though there are substantially more species of reptiles than of amphibians in the world ( 8,734 and 6,347 species respectively).

Similar findings emerged when looking solely at published studies relating to native amphibians and reptiles in the UK. There were, during 2005-2009, 69 “biodiversity and conservation” papers on the seven native British amphibians, compared to just 20 papers on the six native terrestrial reptile species.

“Evidently there has been a significant bias towards study of declines in the amphibians…,” say the paper’s authors. “…the question arises as to whether the bias in favour of amphibian decline research is justified on the basis of risk.”

Though amphibians and reptiles differ in their anatomy and life-histories, the causes of declines and extinctions are similar for both groups of species. They include: habitat loss, invasive wildlife species and disease, pollution, climate change and the impact of roads. Disturbance and persecution (particularly of snakes) are an added cause of concern to reptiles.

Future research into amphibian and reptile declines

To reduce risk of extinctions, the authors suggest that research should focus on the impact that the UK’s changing habitats and landscapes may be having on populations of amphibians and reptiles. This requires detailed ‘baseline’ knowledge about where these species occur, and how individual populations are faring.

In 2007, the National Amphibian and Reptile Recording Scheme (NARRS) was launched to improve understanding of the status of British amphibians and reptiles. The scheme is coordinated by Amphibian and Reptile Conservation and encourages volunteers to survey selected 1km squares for amphibians and reptiles.

“We can base conservation decisions only on robust information,” said NARRS Coordinator Dr. John Wilkinson of Amphibian and Reptile Conservation. “So if you’re looking at getting out and seeing some wildlife, learning new skills and helping protect some of our most threatened creatures, why not take part in NARRS?”